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백승환(Seungwhan Baek),황규완(Gyuwan Hwang),정상권(Sangkwon Jeong) 대한설비공학회 2008 대한설비공학회 학술발표대회논문집 Vol.2008 No.2
The new concept for liquefaction of natural gas has been designed and simulated in this paper. Conventional liquefaction cycles are usually composed with Joule-Thomson valves at lower temperature refrigerant cycle. The new concept of natural gas liquefaction is discussed. The main difference with conventional liquefaction process is the presence of the turbine at low temperature of MR (mixed refrigerant) cycle. The turbine acts as expander but also as an energy generator. This generated energy is provided to the compressor which consumes energy to pressurize refrigerants. The composition of the mixed refrigerant is investigated in this study. Components of the refrigerant are methane, propane and nitrogen. Composition for new process is traced with Aspen HYSYS software. LNG heat exchangers are analyzed for the new process. Heating and cooling curves in heat exchangers were also analyzed.
백승환(Seungwhan Baek),이천규(Cheonkyu Lee),이지성(Jisung Lee),정상권(Sangkwon Jeong) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The microchannel heat exchanger is developed with the Printed Circuit Heat Exchanger (PCHE) fabrication technology. The PCHE is a compact heat exchanger constructed by chemical etching method and diffusion bonding. The PCHE is possible to construct a heat exchanger with a flow channel diameter that is much smaller than that of a commercial plate heat exchanger. The PCHE has an advantage of compactness, therefore it can be utilized as heat exchanger for compact process system such as Liquefied Natural Gas ?Floating Production, Storage and Offloading system, and micro-gas turbine system. However, PCHE also has a disadvantage in performance due to flow maldistribution. The effect of flow mal-distribution has been analyzed with a simple heat exchanger model. The methods to suppress the flow mal-distribution are proposed in this paper.
LNG-FPSO(Liquefied Natural Gas-Floating Production Storage and Offloading)용 질소 팽창 사이클의 효율 개선에 대한 연구
백승환(Seungwhan Baek),정상권(Sangkwon Jeong),김선영(Sunyoung Kim) 대한설비공학회 2010 설비공학 논문집 Vol.22 No.7
FPSO (Floating Production Strorage and Offloading) method for LNG industry is efficient and facile compared to onshore NG (Natural Gas) treatment facility. Five simple natural gas liquefaction cycles for FPSO are presented and simulated in this paper. SMR (Single Mixed Refrigerant) cycle, SNE (Single Nitrogen Expander) cycle, DNE (Double Nitrogen Expander) cycle, PNE (Precooled Nitrogen Expander) cycle, and PDNE (Precooled Double Nitrogen Expander) cycle are compared. Simple analysis results in this paper show that precooling process and adding an expander in the liquefaction cycle is an effective way to increase liquefaction efficiency.
Shell & tube 열교환기에서의 Shell 쪽 유체의 특성에 따른 열교환기 성능 변화 예측 사례
백승환(Seungwhan Baek),정영석(Youngsuk Jung),조기주(Kieejoo Cho) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5
Shell & Tube 열교환기는 일반적인 산업에서 많이 사용되는 열교환기이며, 쉘쪽의 유체와 튜브쪽의 유체가 열을 교환하는 장치이다. 일반적으로 쉘쪽의 유체가 높은 온도와 높은 열용량을 가지고 있다. 열교환기의 구조가 이미 결정이 나 있을 때에, 열교환기의 성능을 향상시키기 위해서는 쉘쪽의 유체의 특성을 바꿔야 한다. Shell & Tube 열교환기가 한국형발사체 개발 사업 중 추진기관종합시험장 (PSTC)에 설치되었으며, 열교환기의 성능을 향상시키기 위한 방법에 대하여 알아본다. Shell & tube heat exchangers are widely used in the industry to heat exchange between shell-side fluid and tube-side fluid. Shell-side fluid are usually high temperature, high heat capacity fluid. When the heat exchanger geometries are once decided, the one and only method to improve heat exchanger performance is to change to shell-side fluid condition. The shell & tube heat exchanger utilized in the Propulsion System Test Complex, and an alternative method to improve heat exchanger performance is discussed in this paper.
백승환(Seungwhan Baek),유이상(Isang Yu),박광근(Kwangkeun Park),정영석(Youngsuk Jung),조기주(Kiejoo Cho),오승협(Seunghyub Oh) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.11
KSLV 상단의 임무의 다각화를 위해서는 저중력 환경에서 액체 추진제의 거동을 정확히 파악하고 있어야 한다. 지상에서 저중력 환경을 모사하는 방법은 자유낙하 방법이 있지만, 공기저항이 항상 동반된다. 공기 저항을 제거하기 위하여 공기 저항 보호막을 이용한 낙하 시험을 진행하였다. 공기 저항 보호막 내부에 시험체를 위치하고 7 m 높이에서 1.2초 동안 낙하하여 시험체의 저중력 환경을 조성하였다. 낙하하는 동안 0.01g 이하의 중력가속도를 측정하였다. 지표면에 도달하기 전 최소 가속도는 약 0.005g였다. 이는 Bremen drop tower에 비하여 0.003g 높은 값이지만, 추후 낙하 높이 및 낙하 시간이 증가한다면 개선될 수 여지가 있다. Understanding of liquid propellant transport phenonma in the low gravity is essential for the development of KSLV upper-stage for the diversity of space mission. The low gravity environment can be simulated by free-fall method on the ground, however, the air-drag is inevitabble. To reduce the air resistance during the free fall, the air-drag shield adopted. In this study, free fall method performed with air-drag shield from 7 m height tower. The acceleration of falling object was measured and analyzed. The low gravity below 0.01g achieved during 1.2 seconds of free fall with the drag shield. The lowest gravitational acceleration value was 0.005g. The minimum gravitational acceleration value was compared with Bremen drop tower experiments, and experimental showed 0.003g higher value. The longer free fall duration may enhance the low gravity quality during the drop experimental.
한국형발사체 축소형 추진기관 시험 설비(R-PSTC) 현황
백승환(Seungwhan Baek),유이상(Isang Yu),박광근(Kwangun Park),정영석(Yungsuk Jung),조기주(Kiejoo Cho),오승협(Seunghyub Oh) 한국추진공학회 2021 한국추진공학회 학술대회논문집 Vol.2021 No.5
한국형발사체 누리호(KSLV-II)는 액체산소와 케로신을 이용한 우주운송수단이다. 발사체의 추진기관 검증 모델 개발을 위하여 축소형 추진기관 시험 설비가 개발되었다. 축소형 추진기관 시험설비는 액체 추진제의 배출 과정을 관찰하는 시험 설비로 액체 추진제 저장탱크와 부수 설비로 이루어져 있다. 추진기관 운용을 위한 추진제 수위 계측 장치, 추진제 소진 감지 장치 또한 검증할 수 있도록 시험 장치를 개발하였다. 고온 헬륨 열교환기가 구비되어 있어 액체 추진기관의 가압 과정을 최대한 유사하게 모사할 수 있다. 본 논문에서는 추진기관 축소형 시험설비의 현황과 운용 결과에 대하여 요약한다. The Korean launch vehicle Nuri is a space transportation vehicle that uses liquid oxygen and kerosene. In order to develop a propulsion engine verification model for a launch vehicle, a reduced propulsion system test complex was developed. The reduced propulsion system test complex is a facility that observes the charge/discharge process of the liquid propellant, and consists of a cryogenic liquid propellant tank and ancillary facilities. Moreover, it can verify the propellant level measurement device and liquid depletion detect device for the operation of the propulsion system. The high-temperature helium heat exchanger allows the simulate the pressurization process of propulsion system as closely as possible. This paper summarizes the current status and operation results of the propulsion engine scale-down test facility.